Magnetic separators arranged to effect a separation of more magnetic particles from less magnetic particles are well known. In an early form, and one which is still employed for the separation of highly magnetic particles, free falling particles are passed through a magnetic field. A separation is created as a result of the lateral movement of the more magnetic particles relative to the less magnetic particles.
In order to treat more weakly magnetic parricles, and extract same, it has been necessary to employ a matrix of magnetic elements, as mentioned above, in order that a stronger magnetic field gradient be created in order to remove, from a through-flow of a fluid mixture, the weakly magnetic particles whilst allowing the substantially non-magnetic particles to pass through the matrix.
Numerous different forms of matrix arrangements have been employed and, in general, the magnetic field is created by the spaced poles of a magnet between which a feed path for the matrix is defined. Such feed path can be defined by an annular container or carousel, arranged either horizontally or vertically, and adapted to rotate with a zone of its circumferential length located between the poles of the magnet.
The presence of the magnetic poles, which must be magnetised by a coil associated therewith, limits the intensity of the magnetic field which can be applied to the matrix of magnetic elements as a result of the attainment of magnetic saturation of the pole forming material.
A further problem which must be mentioned is that slurries, the particles of which are to be separated, often include wood fibres, tramp iron or other contaminants which reduce the effectivenes. If the magnetic separation over a period of time. Indeed, it is advantageous, to regularly wash and clean the matrix of magnetic elements.
As an alternative to the pair of magnetic poles, between which the matrix is passed, there has been proposed a single solenoid coil of the usual annular shape and into which an arcuate portion of a carousel or container extends by reason of its convexity. The inner diameter of the solenoid must, in consequence of this physical arrangement, be substantial relative to the diameter of the carousel or container thus limiting its effectiveness. It is to be mentioned that the matrix could assume any suitable form such as a plurality of separate elements, freely movable relative to each other in the unmagnetised state. The matrix could, however, also be composed of a metal mat or pad or a series of woven metal mesh members.
lt is the object of this invention to provide an improved magnetic separator wherein the intensity of the magnetic yield is improved and, in addition, the means for conveying the matrix of magnetic elements and the nature of the magnetic elements itself may be of an improved nature which facilitates the cleaning of the matrix of the magnetic elements.
In this specification the term two coils is intended to include saddle coils and the like, and the term magnetic is intended to include matter which is capable of acquiring properties of, or being attracted by, a magnet.